The alpine meadow is widely distributed on the Tibetan Plateau with an area of about 1.2×106km2. Damxung County, located in the hinterland of the Tibetan Plateau, is the place covered with this typical vegetation...The alpine meadow is widely distributed on the Tibetan Plateau with an area of about 1.2×106km2. Damxung County, located in the hinterland of the Tibetan Plateau, is the place covered with this typical vegetation. An open-path eddy covariance system was set up in Damxung rangeland station to measure the carbon flux of alpine meadow from July to October, 2003. The continuous carbon flux data were used to analyze the relationship between net ecosystem carbon dioxide exchange (NEE) and photosynthetically active radiation (PAR), as well as the seasonal patterns of apparent quantum yield (α) and maximum ecosystem assimilation (Pmax). Results showed that the daytime NEE fitted fairly well with the PAR in a rectangular hyperbola function, with α declining in the order of peak growth period (0.0244 μmolCO2 · μmol-1PAR) > early growth period > seed maturing period > withering period (0.0098 μmolCO2 · μmol-1PAR). The Pmax did not change greatly during the first three periods, with an average of 0.433 mgCO2 · m-2 · s-1,i.e. 9.829 μmolCO2 · m-2 · s-1. However, during the withering period, Pmax was only 0.35 mgCO2 · m-2 · s-1, i.e. 7.945 μmolCO2 · m-2 · s-1. Compared with other grassland ecosystems, the α of the Tibetan Plateau alpine meadow ecosystem was much lower.展开更多
利用2个耐盐和2个盐敏感的陆地棉品种,分别设置对照和4%(40 g L–1)浓度NaCl溶液处理三叶期幼苗,处理72 h后调查盐害指数,测定地上部分鲜重、根鲜重、叶片相对含水量、叶绿素荧光参数、相对电导率、丙二醛含量、抗氧化酶类活性等13个与...利用2个耐盐和2个盐敏感的陆地棉品种,分别设置对照和4%(40 g L–1)浓度NaCl溶液处理三叶期幼苗,处理72 h后调查盐害指数,测定地上部分鲜重、根鲜重、叶片相对含水量、叶绿素荧光参数、相对电导率、丙二醛含量、抗氧化酶类活性等13个与耐盐性相关的重要指标。利用灰色关联聚类、主成分分析和逐步回归等方法综合评价陆地棉苗期耐盐性,认为最大光化学效率(Fv/Fm)可以作为鉴定陆地棉苗期耐盐性的关键指标,构建耐盐指数(y)方程y=1.943x–0.882(x=最大光化学效率),同时结合另外2个耐盐和2个盐敏感品种所得方程y值对耐盐等级进行划分。进一步利用23个已知耐盐性的品种检验方程,计算结果与田间鉴定结果完全一致。因此选用最大光化学效率作为唯一指标鉴定陆地棉苗期耐盐性,高效准确,同时通过构建方程和划分耐盐等级,为未来大规模陆地棉品种资源耐盐性鉴定提供技术标准和研究基础。展开更多
Net photosynthetic rates(Pn) were measured in 18-month-old seedlings of Machilus pauhoi from two provenances of Suichuan in Jiangxi and Jian’ou in Fujian using a LiCor LI-6400 portable photosynthesis system(LiCor Inc...Net photosynthetic rates(Pn) were measured in 18-month-old seedlings of Machilus pauhoi from two provenances of Suichuan in Jiangxi and Jian’ou in Fujian using a LiCor LI-6400 portable photosynthesis system(LiCor Inc.,Lincoln,NE,USA) with a LED light source. The other photosynthetic parameters,including maximum net photosynthetic rate(Pmax),apparent quantum yield(AQY),light saturation point(LSP) and light compensation point(LCP),were also detected in response to irradiation. The results showed: The average P max,AQY,LSP and LCP of the seedlings from the two provinces were 12.65 μmolCO2.m -2 s -1,0.052 7 μmolCO2.μmol -1 photons,1 120.99 μmol.m -2 s -1 and 18.03 μmol.m -2 s -1 respectively. There were significant differences between the two provenances in the all photosynthetic parameters except for AQY. The provenance of Suichuan performed better than that from Jian’ou with higher P max,AQY and LSP of 30.48%,4.66% and 25.70% respectively,though the LCP of Suichuan provenance was higher and needed stronger illumination. There was more variation in P max,AQY,LSP and LCP between the two provenances than that within the two provenances. There were significant differences between the upper and lower crown layers with higher P max and AQY in the upper crown,while there was no difference in LCP and LSP between the two crown layers due to the integrated influence of the shape of seedling crowns and the photosensitivity of leaves.展开更多
THE responses of plant photosynthesis to elevated CO<sub>2</sub> could be divided into short-term re-sponse and long-term response or acclimation.In the short-term response,photosynthesiscan be enhanced at...THE responses of plant photosynthesis to elevated CO<sub>2</sub> could be divided into short-term re-sponse and long-term response or acclimation.In the short-term response,photosynthesiscan be enhanced at the beginning of high CO<sub>2</sub> treatment for most C<sub>3</sub> carbon fixation species,but the photosynthetic rate may decrease when the plants are exposed to that high CO<sub>2</sub> for展开更多
基金This work was jointly supported by the Major State Basic Research Development Program of China(Grant No.2002CB412501)the National Natural Science Foundation of China(Grant Nos.30170153 and 30470280)the Key Innovation Project of Institute of Geographic Sciences and Natural Resources Research,CAS(Grant No.CXIOG-E01-03-03).
文摘The alpine meadow is widely distributed on the Tibetan Plateau with an area of about 1.2×106km2. Damxung County, located in the hinterland of the Tibetan Plateau, is the place covered with this typical vegetation. An open-path eddy covariance system was set up in Damxung rangeland station to measure the carbon flux of alpine meadow from July to October, 2003. The continuous carbon flux data were used to analyze the relationship between net ecosystem carbon dioxide exchange (NEE) and photosynthetically active radiation (PAR), as well as the seasonal patterns of apparent quantum yield (α) and maximum ecosystem assimilation (Pmax). Results showed that the daytime NEE fitted fairly well with the PAR in a rectangular hyperbola function, with α declining in the order of peak growth period (0.0244 μmolCO2 · μmol-1PAR) > early growth period > seed maturing period > withering period (0.0098 μmolCO2 · μmol-1PAR). The Pmax did not change greatly during the first three periods, with an average of 0.433 mgCO2 · m-2 · s-1,i.e. 9.829 μmolCO2 · m-2 · s-1. However, during the withering period, Pmax was only 0.35 mgCO2 · m-2 · s-1, i.e. 7.945 μmolCO2 · m-2 · s-1. Compared with other grassland ecosystems, the α of the Tibetan Plateau alpine meadow ecosystem was much lower.
文摘用美国Li-Cor公司生产的Li-6400光合作用测定仪控制CO2浓度和温度,测量了华北平原冬小麦(Triticum aestivum)的光响应数据。分别用C3植物光响应新模型、直角双曲线模型、非直角双曲线模型和Prado-Moraes模型拟合这些实测数据,分析了由直角双曲线模型、非直角双曲线模型和Prado-Moraes模型拟合这些数据得到的最大净光合速率(The maximum net photosynthetic rate)远大于实测值,而光饱和点(Light saturation point)远小于实测值的原因。结果表明,由C3植物光响应新模型拟合的结果与实测数据符合程度最高(R2=0.9994和R2=0.9987);表观量子效率(Apparent quantum yield)不是一个理想的表示植物利用光能的指标,建议用植物光响应曲线在光补偿点处的量子效率作为表示植物光能利用的指标。
文摘利用2个耐盐和2个盐敏感的陆地棉品种,分别设置对照和4%(40 g L–1)浓度NaCl溶液处理三叶期幼苗,处理72 h后调查盐害指数,测定地上部分鲜重、根鲜重、叶片相对含水量、叶绿素荧光参数、相对电导率、丙二醛含量、抗氧化酶类活性等13个与耐盐性相关的重要指标。利用灰色关联聚类、主成分分析和逐步回归等方法综合评价陆地棉苗期耐盐性,认为最大光化学效率(Fv/Fm)可以作为鉴定陆地棉苗期耐盐性的关键指标,构建耐盐指数(y)方程y=1.943x–0.882(x=最大光化学效率),同时结合另外2个耐盐和2个盐敏感品种所得方程y值对耐盐等级进行划分。进一步利用23个已知耐盐性的品种检验方程,计算结果与田间鉴定结果完全一致。因此选用最大光化学效率作为唯一指标鉴定陆地棉苗期耐盐性,高效准确,同时通过构建方程和划分耐盐等级,为未来大规模陆地棉品种资源耐盐性鉴定提供技术标准和研究基础。
文摘Net photosynthetic rates(Pn) were measured in 18-month-old seedlings of Machilus pauhoi from two provenances of Suichuan in Jiangxi and Jian’ou in Fujian using a LiCor LI-6400 portable photosynthesis system(LiCor Inc.,Lincoln,NE,USA) with a LED light source. The other photosynthetic parameters,including maximum net photosynthetic rate(Pmax),apparent quantum yield(AQY),light saturation point(LSP) and light compensation point(LCP),were also detected in response to irradiation. The results showed: The average P max,AQY,LSP and LCP of the seedlings from the two provinces were 12.65 μmolCO2.m -2 s -1,0.052 7 μmolCO2.μmol -1 photons,1 120.99 μmol.m -2 s -1 and 18.03 μmol.m -2 s -1 respectively. There were significant differences between the two provenances in the all photosynthetic parameters except for AQY. The provenance of Suichuan performed better than that from Jian’ou with higher P max,AQY and LSP of 30.48%,4.66% and 25.70% respectively,though the LCP of Suichuan provenance was higher and needed stronger illumination. There was more variation in P max,AQY,LSP and LCP between the two provenances than that within the two provenances. There were significant differences between the upper and lower crown layers with higher P max and AQY in the upper crown,while there was no difference in LCP and LSP between the two crown layers due to the integrated influence of the shape of seedling crowns and the photosensitivity of leaves.
文摘THE responses of plant photosynthesis to elevated CO<sub>2</sub> could be divided into short-term re-sponse and long-term response or acclimation.In the short-term response,photosynthesiscan be enhanced at the beginning of high CO<sub>2</sub> treatment for most C<sub>3</sub> carbon fixation species,but the photosynthetic rate may decrease when the plants are exposed to that high CO<sub>2</sub> for
